1. Field of the Invention
The invention relates generally to jar devices for use during downhole fishing operations and the like and more particularly, but not by way of limitation, it relates to a dual acting hydraulic jar device that can be actuated through coiled tubing by both lift-up and set-down of supporting string weight.
2. Description of the Prior Art
There have been various forms of prior art jar devices which are extremely effective in loosening stuck pipe by providing a hammer type impact at a desired downhole location. Prior jarring devices are commonly run in conjunction with overshots, spears, etc., to aid in loosening a fish object once it has been caught or secured. Such jarring devices generally utilize energy of compressed fluids to drive a free-moving piston or hammer against the top of the jar device, which fluid compression is obtained by surface movement of the drill pipe or tubing string. Thus, there are various types of hydraulic, mechanical and hydromechanical drilling jars as well as dual acting hydraulic jars that have been utilized in the past, and there is even an up-down jar device which employs both a mechanically operated unit to deliver the down jar and a hydraulically operated unit for delivering the up jar. To Applicants' knowledge there have not been any dual acting hydraulic coil tubing jars.